It is conventional practice in plant breeding or plant advancement experiments to grow plants from seeds of known parentage. The seeds are planted in experimental plots, growth chambers, greenhouses, or other growing conditions in which they are either cross pollinated with other plants of known parentage or self pollinated. The resulting seeds are the offspring of the two parent plants or the self pollinated plant, and are harvested, processed and planted to continue the plant breeding cycle. Specific laboratory or field-based tests may be performed on the plants, plant tissues, seed or seed tissues, in order to aid in the breeding or advancement selection process.
Generations of plants based on known crosses or self pollinations are planted and then tested, such as through trait purity tests, to see if these lines or varieties are moving toward characteristics that are desirable in the marketplace. Examples of desirable traits include, but are not limited to, increased yield, increased homozygosity, improved or newly conferred resistance and/or tolerance to specific herbicides and/or pests and pathogens, increased oil content, altered starch content, nutraceutical composition, drought tolerance, and specific morphological based trait enhancements.
Often, seeds having desirable characteristics are produced commercially for sale in the marketplace. In such instances, quality control tests, such as genetic purity tests, may be conducted to determine that the seeds indeed comprise the advertised genetic composition. In many instances, a certain number of seeds may be sampled from each bag of seeds produced. For example, it is not uncommon to test approximately one hundred seeds from each production bag in order to verify the genetic composition of the seeds from the bag. For some seed types, such as those in large production, this can translate to over one million individual seeds to be sampled.
In order to test the genetic composition of the seeds, samples of the individual seeds themselves, or of the plants that develop from the seeds, are gathered. For example, in one method, a hole is drilled in a small location on the seed and the debris from the seed is removed. The debris is then transferred to a test tube or other container and analyzed. Another method is described in V. Sangtong, E. C. Mottel, M. J. Long, M. Lee, and M. P. Scott, Serial Extraction of Endosperm Drillings (SEED)—A Method for Detecting Transgenes and Proteins in Single Viable Maize Kernels, Plant Molecular Biology Reporter 19: 151-158, June 2001, in which a hand-held rotary grinder is used to grind off so-called “drillings” from each kernel.
Automated seed grinding techniques also exist to generate seed samples. For example, in one method a blade grinder (or cutting mill) may be used to grind one or more seeds into a group of seed particles. In general, a typical blade grinder includes a chamber into which the one or more seeds may be placed, and one or more blades that are configured to rotate within the chamber such that they act upon the seed(s) so as to reduce the seed(s) into a group of seed particles. In another method, a shaker grinder (or ball mill) may be used to crush one or more seeds into a group of seed particles. In general, a typical shaker grinder includes a chamber into which the one or more seeds may be placed, and one or more “balls” that are placed into the chamber along with the seed(s). The chamber is then vibrated in such a manner that the grinding balls act upon the seed(s) to reduce the seed(s) into the group of seed particles.
For each of these methods, the seed samples are transferred by hand to a testing apparatus where the tissue samples from the seed(s) are analyzed for DNA or protein composition. Many procedures exist whereby various proteins or cell DNA may be extracted from the samples. For example, a typical method may include placing a seed sample into an extraction well and subjecting the seed sample cells to a cell lysis solution such that the cell walls are broken down to release the DNA and proteins into the resulting solution. A buffer may then be added that is formulated to separate the DNA from the proteins. At this point either the DNA or the protein may be extracted for further testing.
The above methods of obtaining seed samples from the seed chambers and transferring the samples to the testing apparatuses are extremely time consuming and involve numerous manual processes. In addition, it is difficult to obtain seed samples having repeatable sample sizes. As a result, there is a need for an improved system and method for obtaining tissue samples from one or more seeds. In various embodiments, the system and method should provide an efficient manner of gathering seed samples for further processing, such as DNA and protein purification and extraction, and it should also provide normalized seed sample sizes.